Incremental gateway deployment in a hub-spoke satellite communication system using static spot beams

ABSTRACT

A method for communicating includes providing a hub-spoke satellite comprising receivers, transmitters, transmit switches, and a gateway switch structure. Prior to a time T, each of at least P receivers are used to receive one of at least P signals from P gateway terminals. During one frame, the gateway switch structure is used to switch the at least P signals to the plurality of transmit switches. Each of the at least P signals are switched into fixed location beams. After time T, each of at least Q receivers are used to receive a different one of at least Q signals from Q gateway terminals. During one frame, the gateway switch structure is used to switch the at least Q signals to the plurality of transmit switches. Each of the at least Q signals are switched into fixed location beams. Q and P are non-zero positive integers and Q&gt;P.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of International ApplicationNo. PCT/US2012/048695, filed Jul. 27, 2012, which claims benefit ofpriority of U.S. Provisional Application Nos. 61/513,317, filed Jul. 29,2011; 61/568,569, filed Dec. 8, 2011; 61/568,578, filed Dec. 8, 2011;and 61/591,810, filed Jan. 27, 2012; the entire contents of which areincorporated herein by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to satellite communicationsystems and, more particularly, to incremental gateway deployment in ahub-spoke satellite communication system using static (e.g., fixedlocation) spot beams.

BACKGROUND

A hub-spoke satellite communication system typically includes aconstellation of satellites that link gateway terminals with usersterminals. The gateway terminals provide an interface with a networksuch as the Internet or a public switched telephone network. Eachgateway terminal typically services a number of user terminals locatedin one or more spot beams.

Hub-spoke satellite communication systems have a high initial cost.Before user terminals can be serviced, hub-spoke spot beam satellitesmust be built and launched and the gateway terminals must be deployed.After service is initiated, it takes time to build up a subscriber base.During this initial startup period, the system is utilized at less thanfull capacity.

SUMMARY

Some embodiments of the present invention provide incremental gatewaydeployment in a hub-spoke satellite communication system using fixedlocation beams.

In accordance with an embodiment of the invention, a method forcommunicating using a hub-spoke satellite having a forward linkcapability includes providing the hub-spoke satellite. The hub-spokesatellite may include a plurality of receivers having inputs and outputsand a plurality of transmitters having inputs and outputs. The inputs ofthe plurality of transmitters may be coupled to the outputs of theplurality of receivers. A plurality of transmit switches may be coupledto the outputs of the plurality of transmitters. The hub-spoke satellitemay also include a gateway switch structure coupled to one of: (a) theinputs of the plurality of receivers, and (b) the outputs of theplurality receivers and the inputs of the plurality of transmitters.Each transmit switch in the plurality of transmit switches may be usedto sequentially switch a forward link signal into multiple fixedlocation beams according to a beam group transmit switching pattern.Prior to a time T, the method may include using each of at least Preceivers in the plurality of receivers to receive a different one of atleast P forward link signals from P gateway terminals. In the durationof one frame, the gateway switch structure may be used to sequentiallyswitch the at least P forward link signals from the P gateway terminals,in order to provide the at least P forward link signals to the pluralityof transmit switches, according to a first gateway switching pattern.The gateway switch structure may also be used to sequentially switcheach of the at least P forward link signals into fixed location beamsaccording to a first beam group transmit switching pattern. After timeT, the method may include using each of at least Q receivers in theplurality of receivers to receive a different one of at least Q forwardlink signals from Q gateway terminals. In the duration of one frame, thegateway switch structure may be used to sequentially switch the at leastQ forward link signals from the Q gateway terminals, in order to providethe at least Q forward link signals to the plurality of transmitswitches, according to a second gateway switching pattern. The gatewayswitch structure may also be used to sequentially switch each of the atleast Q forward link signals into fixed location beams according to asecond beam group transmit switching pattern. P and Q may both benon-zero, positive integers, and Q>P. The first and second gatewayswitching patterns may be different.

In an embodiment, the at least P receivers may consist of exactly Preceivers, and the P gateway terminals may each transmit one signal on asingle polarization.

In another embodiment, the at least P receivers may consist of exactly2*P receivers, and the P gateway terminals may each transmit two signalson two different polarizations.

In another embodiment, the gateway switch structure may include a switchmatrix positioned between the plurality of receivers and the pluralityof transmitters.

In another embodiment, the gateway switch structure may include at leastone receive-side outer switch positioned before the plurality ofreceivers. In some embodiments, the plurality of receivers may include Rreceivers, where R is a non-zero, positive integer, and R>=Q>P. The atleast one receive-side outer switch may include one 1:R switch forreceiving a first forward link signal, the 1:R switch associated with afirst switching speed allowing switching within the duration of oneframe. The at least one receive-side outer switch may also include aplurality of 2:1 switches, each for receiving (a) an output of the 1:Rswitch and (b) one of R−1 other forward link signals. Each of theplurality of 2:1 switches may be associated with a second switchingspeed allowing switching at time T. In other embodiments, the pluralityof receivers may include R receivers, where R is a non-zero, positiveinteger, and R>=Q>P. The at least one receive-side outer switch mayinclude a first bank of switches, including 1:R, 1:(R−1), . . . , 1:2switches, each associated with a first switching speed allowingswitching within the duration of one frame. The at least onereceive-side outer switch may also comprise a second bank of switchesfollowing the first bank of switches, the second bank of switchesincluding 2:1, 3:1, . . . , (R−1):1 switches, each associated with asecond switching speed allowing switching at time T. The second bank ofswitches may further include an R:1 switch associated with the firstswitching speed allowing switching within the duration of one frame. Inyet other embodiments, the plurality of receivers may comprise Rreceivers, where R is a non-zero, positive integer, and R>=Q>P. The atleast one receive-side outer switch may comprise a first bank ofswitches, including a 1:R switch and a 1:(R/2) switch, each associatedwith a first switching speed allowing switching within the duration ofone frame. The at least one receive-side outer switch may also comprisea second bank of switches following the first bank of switches, eachassociated with a second switching speed allowing switching at time T.

In another embodiment, each of the plurality of receivers may comprise alow noise amplifier (LNA).

In another embodiment, each of plurality of transmitters may comprise ahigh power amplifier (HPA).

In another embodiment, the first and second beam group transmitswitching patterns may be different.

In another embodiment, the first and second beam group transmitswitching patterns may be the same.

In yet another embodiment, the hub-spoke satellite may have return linkcapability in addition to forward link capability and further comprise aplurality of receive switches coupled to the inputs of the plurality ofreceivers. The gateway switch structure may be coupled to one of: (a)the inputs of the plurality of receivers and the outputs of theplurality of transmitters, and (b) the outputs of the pluralityreceivers and the inputs of the plurality of transmitters. Each receiveswitch in the plurality of receive switches may be used to sequentiallyswitch return link signals from fixed location beams into a receiveraccording to a beam group receive switching pattern. Prior to time T,the method may include sequentially switching the return link signalsfrom multiple fixed location beams into the plurality of receiversaccording to a first beam group receive switching pattern. In theduration of one frame, the gateway switch structure may be used tosequentially switch the return link signals to at least P transmittersin the plurality of transmitters according to the first gatewayswitching pattern. Each of the at least P transmitters may be used totransmit a different one of the return link signals to one of the Pgateway terminals. After time T, the method may include sequentiallyswitching the return link signals from multiple fixed location beamsinto the plurality of receivers according to a second beam group receiveswitching pattern. In the duration of one frame, the gateway switchstructure may be used to sequentially switch the return link signals toat least Q transmitters in the plurality of transmitters according tothe second gateway switching pattern. Each of the at least Qtransmitters may be used to transmit a different one of the return linksignals to one of the Q gateway terminals.

In accordance with another embodiment of the invention, a satellitecommunication system having a forward link capability may include aplurality of gateway terminals, a plurality of user terminals, and ahub-spoke satellite for providing communications between the gatewayterminals and the user terminals. The hub-spoke satellite may comprise aplurality of receivers having inputs and outputs and a plurality oftransmitters having inputs and outputs. The inputs of the plurality oftransmitters may be coupled to the outputs of the plurality ofreceivers. A plurality of transmit switches may be coupled to theoutputs of the plurality of transmitters. A gateway switch structure maybe coupled to one of: (a) the inputs of the plurality of receivers, and(b) the outputs of the plurality receivers and the inputs of theplurality of transmitters. Each transmit switch in the plurality oftransmit switches may be configured to sequentially switch a forwardlink signal into multiple fixed location beams according to a beam grouptransmit switching pattern. Prior to a time T, at least P receivers inthe plurality of receivers may each be configured to receive a differentone of at least P forward link signals from P gateway terminals. In theduration of one frame, the gateway switch structure may be configured tosequentially switch the at least P forward link signals from the Pgateway terminals, in order to provide the at least P forward linksignals to the plurality of transmit switches, according to a firstgateway switching pattern. Each of the at least P forward link signalsmay be sequentially switched into fixed location beams according to afirst beam group transmit switching pattern. After time T, at least Qreceivers in the plurality of receivers may each be configured toreceive a different one of at least Q forward link signals from Qgateway terminals. In the duration of one frame, the gateway switchstructure may be configured to sequentially switch the at least Qforward link signals from the Q gateway terminals, in order to providethe at least Q forward link signals to the plurality of transmitswitches, according to a second gateway switching pattern. Each of theat least Q forward link signals may be sequentially switched into fixedlocation beams according to a second beam group transmit switchingpattern. P and Q may both be non-zero, positive integers, and Q>P. Thefirst and second gateway switching patterns may be different.

In accordance with another embodiment of the invention, a hub-spokesatellite having a forward link capability may include a plurality ofreceivers having inputs and outputs and a plurality of transmittershaving inputs and outputs. The inputs of the plurality of transmittersmay be coupled to the outputs of the plurality of receivers. A pluralityof transmit switches may be coupled to the outputs of the plurality oftransmitters. Each transmit switch in the plurality of transmit switchesmay be configured to sequentially switch a forward link signal intomultiple fixed location beams according to a beam group transmitswitching pattern. A gateway switch structure may be coupled to one of:(a) the inputs of the plurality of receivers, and (b) the outputs of theplurality receivers and the inputs of the plurality of transmitters.Prior to a time T, at least P receivers in the plurality of receiversmay each be configured to receive a different one of at least P forwardlink signals from P gateway terminals. In the duration of one frame, thegateway switch structure may be configured to sequentially switch the atleast P forward link signals from the P gateway terminals, in order toprovide the at least P forward link signals to the plurality of transmitswitches, according to a first gateway switching pattern. Each of the atleast P forward link signals may be sequentially switched into fixedlocation beams according to a first beam group transmit switchingpattern. After time T, at least Q receivers in the plurality ofreceivers may each be configured to receive a different one of at leastQ forward link signals from Q gateway terminals. In the duration of oneframe, the gateway switch structure may be configured to sequentiallyswitch the at least Q forward link signals from the Q gateway terminals,in order to provide the at least Q forward link signals to the pluralityof transmit switches, according to a second gateway switching pattern.Each of the at least Q forward link signals is sequentially switchedinto fixed location beams according to a second beam group transmitswitching pattern. P and Q may both be non-zero, positive integers, andQ>P. The first and second gateway switching patterns may be different.

In accordance with yet another embodiment, a hub-spoke satellite havinga forward link capability may include, prior to a time T, means forreceiving at least P forward link signals from P gateway terminals,means for sequentially switching the at least P forward link signalsfrom the P gateway terminals in the duration of one frame, in order toprovide the at least P forward link signals to a plurality of transmitswitches, according to a first gateway switching pattern, and means forsequentially switching each of the at least P forward link signals intofixed location beams according to a first beam group transmit switchingpattern. The hub-spoke satellite having the forward link capability mayalso include, after time T, means for receiving at least Q forward linksignals from Q gateway terminals, means for sequentially switching theat least Q forward link signals from the Q gateway terminals in theduration of one frame, in order to provide the at least Q forward linksignals to the plurality of transmit switches, according to a secondgateway switching pattern, and means for sequentially switching each ofthe at least Q forward link signals into fixed location beams accordingto a second beam group transmit switching pattern. P and Q may both benon-zero, positive integers, and Q>P. The first and second gatewayswitching patterns may be different.

BRIEF DESCRIPTION OF THE DRAWINGS

In some of the drawings a sub-label is associated with a referencenumeral and follows a hyphen to denote one of multiple similarcomponents. When reference is made to a reference numeral withoutspecifying an existing sub-label, it is intended to refer to all suchsimilar components.

FIG. 1 is a simplified diagram of a hub-spoke satellite communicationsystem in accordance with an embodiment of the present invention;

FIGS. 2A-2C are simplified block diagrams of pathways in accordance withsome embodiments of the present invention;

FIG. 3 is a simplified block diagram of example hardware that services aGW switch group in accordance with an embodiment of the presentinvention;

FIG. 4 is a simplified block diagram of a GW switch group embodiment,employing a switch matrix to provide incremental gateway deployment forforward and return link capability at a hub-spoke satellite inaccordance with an embodiment of the present invention;

FIG. 5 is a simplified block diagram of a GW switch group embodimentusing an outer switch structure that may be used to provide incrementalgateway deployment for forward and return link capability at a hub-spokesatellite in accordance with an embodiment of the present invention; and

FIGS. 6-8 are simplified block diagrams of various outer switch networksembodiments that may be used to enable incremental gateway deploymentfor forward and return link capability at a hub-spoke satellite inaccordance with some embodiments of the present invention.

DETAILED DESCRIPTION

To provide high capacity over large coverage areas, a hub-spokesatellite system may employ a large number of focused user spot beamsthat illuminate user terminals. These user terminals may be serviced bygateway terminals that provide an interface to data services such asvoice, video, web browsing, email, etc. Gateway terminals are typicallyassociated with a specific spot beam (or beams) and the deployment of anassociated gateway is required before providing service to its user spotbeam coverage area. Embodiments of the present invention provideincremental gateway deployment such that service may be provided tocoverage areas associated with other gateways up to and including thefull coverage area of the satellite system. The capacity is stilllimited to the capability of the deployed gateways, but additionalgateway terminals may be added over time to increase capacity up to themaximum capacity.

Reference will now be made to the exemplary embodiments illustrated inthe drawings, and specific language will be used herein to describe thesame. It will nevertheless be understood that no limitation of the scopeof the invention is thereby intended. Alterations and furthermodifications of the inventive features illustrated herein, andadditional applications of the principles of the inventions asillustrated herein, which would occur to one skilled in the relevant artand having possession of this disclosure, are to be considered withinthe scope of the invention.

In describing the present invention, the following terminology will beused: The singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to an item includes reference to one or more items. The term“ones” refers to one, two, or more, and generally applies to theselection of some or all of a quantity. The term “plurality” refers totwo or more of an item. The term “about” means quantities, dimensions,sizes, formulations, parameters, shapes and other characteristics neednot be exact, but may be approximated and/or larger or smaller, asdesired, reflecting acceptable tolerances, conversion factors, roundingoff, measurement error and the like and other factors known to those ofskill in the art. The term “substantially” means that the recitedcharacteristic, parameter, or value need not be achieved exactly, butthat deviations or variations including, for example, tolerances,measurement error, measurement accuracy limitations and other factorsknown to those of skill in the art, may occur in amounts that do notpreclude the effect the characteristic was intended to provide.Numerical data may be expressed or presented herein in a range format.It is to be understood that such a range format is used merely forconvenience and brevity and thus should be interpreted flexibly toinclude not only the numerical values explicitly recited as the limitsof the range, but also interpreted to include all of the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. As an illustration,a numerical range of “about 1 to 5” should be interpreted to include notonly the explicitly recited values of about 1 to about 5, but alsoinclude individual values and sub-ranges within the indicated range.Thus, included in this numerical range are individual values such as 2,3 and 4 and sub-ranges such as 1-3, 2-4 and 3-5, etc. This sameprinciple applies to ranges reciting only one numerical value (e.g.,“greater than about 1”) and should apply regardless of the breadth ofthe range or the characteristics being described. A plurality of itemsmay be presented in a common list for convenience. However, these listsshould be construed as though each member of the list is individuallyidentified as a separate and unique member. Thus, no individual memberof such list should be construed as a de facto equivalent of any othermember of the same list solely based on their presentation in a commongroup without indications to the contrary. Furthermore, where the terms“and” and “or” are used in conjunction with a list of items, they are tobe interpreted broadly, in that any one or more of the listed items maybe used alone or in combination with other listed items. The term“alternatively” refers to selection of one of two or more alternatives,and is not intended to limit the selection to only those listedalternatives or to only one of the listed alternatives at a time, unlessthe context clearly indicates otherwise.

The term “coupled” as used herein does not require that the componentsbe directly connected to each other. Instead, the term is intended toalso include configurations with indirect connections where one or moreother components may be included between coupled components. Forexample, such other components may include amplifiers, attenuators,isolators, directional couplers, redundancy switches, and the like.

FIG. 1 is a simplified diagram of a hub-spoke satellite communicationsystem 100 in accordance with an embodiment of the present invention.The satellite communication system 100 includes a satellite 105 linkinga gateway terminal 115 with one or more user terminals 130. Thesatellite communication system 100 may use a number of networkarchitectures consisting of space and ground segments. The space segmentmay include more than one satellite while the ground segment may includea large number of user terminals, gateway terminals, network operationscenters (NOCs), satellite and gateway terminal command centers, and thelike. These elements are not shown in the figure for clarity.

The gateway terminal 115 is sometimes referred to as a hub or groundstation. The gateway terminal 115 may service communication links 135,140 between the gateway terminal 115 and the satellite 105. The gatewayterminal 115 may also schedule traffic to the user terminals 130.Alternatively, the scheduling may be performed in other parts of thesatellite communication system 100 (e.g., at one or more NOCs and/orgateway command centers—neither of which are shown in this embodiment).

The gateway terminal 115 may also provide an interface between a network120 and the satellite 105. The gateway terminal 115 may receive data andinformation from the network 120 that is directed the user terminals130. The gateway terminal 115 may format the data and information fordelivery to the user terminals 130 via the satellite 105. The gatewayterminal 115 may also receive signals carrying data and information fromthe satellite 105. This data and information may be from the userterminals 130 and directed to destinations accessible via the network120. The gateway terminal 115 may format this data and information fordelivery via the network 120.

The network 120 may be any type of network and may include, for example,the Internet, an IP network, an intranet, a wide-area network (WAN), alocal-area network (LAN), a virtual private network (VPN), a publicswitched telephone network (PSTN), a public land mobile network, and thelike. The network 120 may include both wired and wireless connections aswell as optical links. The network 120 may connect the gateway terminal115 with other gateway terminals that may be in communication with thesatellite 105 or with other satellites.

The gateway terminal 115 may use one or more antennas 110 to transmitforward uplink signals 135 to the satellite 105 and to receive returndownlink signals 140 from the satellite 105. The antenna 110 shown inFIG. 1 includes a reflector with high directivity in the direction ofthe satellite 105 and low directivity in other directions. The antenna110 may be implemented in a variety of alternative configurations andinclude operating features such as high isolation between orthogonalpolarizations, high efficiency in the operational frequency bands, lownoise, and the like.

In some satellite communication systems there may be a limited frequencyspectrum available for transmission. Communication links 135, 140between the gateway terminal 115 and the satellite 105 may use the same,overlapping, or different frequencies compared to the communicationlinks 145, 150 between the satellite 105 and the user terminals 130. Insome embodiments, the gateway terminal 115 may be located away from theuser terminals 130, which enables frequency re-use. In otherembodiments, the user terminals 130 may be located near the gatewayterminal 115.

The satellite 105 may be a geostationary satellite that is configured toreceive and transmit signals. The satellite 105 may receive the forwarduplink signals 135 from the gateway terminal 115 and transmitscorresponding forward downlink signals 150 to the user terminals 130.The satellite 105 may also receive return uplink signals 145 from theuser terminals 130 and transmits corresponding return downlink signals140 to the gateway terminal 115.

The satellite 105 may include one or more fixed directional antennas forreception and transmission of the signals 135, 140, 145, 150. Adirectional antenna may include a fixed reflector with one or more feedhorns for each spot beam. The feed horns may be employed for receivinguplink signals 135, 145 and transmitting downlink signals 140, 150. Thefixed feed of a directional antenna is in contrast to a more complexphased-array antenna that includes a number of phase combiners connectedto a number of antenna elements.

A spot beam may be a path along which a signal travels to or from thesatellite 105. Contours of a spot beam may be determined in part by theparticular antenna design and depend on factors such as location of feedhorn relative to a reflector, size of the reflector, type of feed horn,etc. Each spot beam may generally have a conical shape (typicallycircular or elliptical) that extends between the antenna and earth,illuminating a spot beam coverage area for both transmit and receiveoperations. A spot beam coverage area generally corresponds to anintersection between a spot beam and the earth's surface and mayilluminate terminals that are not on the earth surface such as airborneuser terminals, etc. In some embodiments, directional antennas may beused to form fixed location spot beams (or spot beams that areassociated with substantially the same spot beam coverage area overtime). This is in contrast to dynamic phased-array antennas that may beused to almost instantly change spot beam locations and their associatedspot beam coverage areas. The directional antenna may be repointed,typically by mechanical means, but not fast enough to allow capacityflexibility as discussed herein.

The satellite 105 may operate in a multiple spot-beam mode, receivingand transmitting a number of signals in different spot beams. In theembodiment shown in FIG. 1, the gateway 115 and the user terminals 130may be within the same or different spot beams. Each spot beam may use asingle carrier (i.e., one carrier frequency), a contiguous frequencyrange, or a number of frequency ranges.

The satellite 105 may include a number of non-regenerative pathways(represented as K pathways in this embodiment). Each of the K pathwaysmay be allocated as a forward pathway or a return pathway at any giveninstant in time. The uplink signals 135, 145 received by the satellite105 may be directed along one or more of the pathways before beingtransmitted as downlink signals 140, 150.

The signals are not demodulated and re-modulated as in a regenerative orprocessing satellite architecture. Instead, signal manipulation by anon-regenerative satellite is generally limited to functions such asfrequency translation, polarization conversion, filtering,amplification, and the like.

The forward downlink signals 150 may be transmitted from the satellite105 to one or more of the user terminals 130. The user terminals 130 mayreceive the forward downlink signals 150 using antennas 127. In oneembodiment, an antenna and a user terminal together comprise a verysmall aperture terminal (VSAT) with the antenna measuring approximately0.75 meters in diameter and having approximately 2 watts of power. Inother embodiments, a variety of other types of antennas 127 may be usedto receive the forward downlink signals 150 from the satellite 105. Eachof the user terminals 130 may comprise a single user terminal or a hubor router coupled to other user terminals. Each of the user terminals130 may be connected to various consumer premises equipment (CPE) suchas computers, local area networks, internet appliances, wirelessnetworks, and the like.

The user terminals 130 may transmit data and information to adestination accessible via the network 120. The user terminals 130 maytransmit the return uplink signals 145 to the satellite 105 using theantennas 127. The user terminals 130 may transmit the signals accordingto a variety of physical layer transmission, modulation and codingtechniques including, for example physical layer signaling defined bystandards such as, DVB (e.g. DVB-S2, DVB-RCS), WiMAX, LTE, DOCSIS, andsimilar standards in their native or adapted (modified) forms. Invarious embodiments, the physical layer techniques may be the same ordifferent for each of the links 135, 140, 145, 150.

FIGS. 2A-2C are simplified block diagrams of pathways in accordance withsome embodiments of the present invention. These pathways may correspondto some of the K pathways shown in FIG. 1. In general, the pathways mayprovide for conversion of uplink signals received by the satellite intodownlink signals. Each of the pathways may include a receiver (Rx) andby a transmitter (Tx). The receiver may include an LNA, and thetransmitter may include an HPA. The receiver and transmitter are notlimited to these components, however, and may include other componentsas well. For example, in some embodiments the receiver and/or thetransmitter may also include components that provide frequencyconversion (e.g., a down converter), filtering, and the like. Thespecific components included in each pathway and the configuration ofthose components may vary depending on the particular application.

The satellite communication system may use a framed hub-spoke beamswitched pathway access protocol, with time slots like a SatelliteSwitched Time-Division Multiple Access (SSITDMA) scheme. However, eachtime slot of the frame may correspond to either forward link (gateway touser terminals) or return link (user terminals to gateway) traffic froma transmitting beam to a receiving beam—not just a single transmissionfrom one terminal to another. During normal operation, continuousstreams of frames are typically used to facilitate communications.Multiple terminals may be serviced during each time slot using wellknown multiplexing and multiple access techniques (e.g., Time-DivisionMultiplexing (TDM), Time-Division Multiple Access (TDMA),Frequency-Division Multiple Access (FDMA), Multi-Frequency Time-DivisionMultiple Access (MF-TDMA), Code-Division Multiple Access (CDMA), and thelike).

Forward Pathways

FIG. 2A provides an example of a forward pathway in accordance with anembodiment. In this embodiment, a receiver may be configured to receiveforward uplink signals from a gateway via a gateway beam feed (GW/UFeed). In forward operation, the gateway beam feed may receive signalsfrom one or more gateway terminals (e.g., gateway terminal 115 of FIG.1). The output of the receiver may be coupled to the input of atransmitter.

The transmitter is coupled to a transmit switch (Tx SW). The transmitswitch may be used to control an output from the pathway. The transmitswitch may be positioned after the transmitter of the pathway along asignal path. The transmit switch may dynamically switch the transmissionsignal between any one of N user beam feeds (User Feeds) or a gatewaybeam feed (GW/U Feed). Each of the N user beam feeds may provide signalsto one or more user terminals (e.g., user terminals 130 of FIG. 1). Thegateway beam feed may provide signals to user terminals that are locatedwithin the same spot beam coverage area as the gateway terminal (hencethe designation “GW/U”). The set of beams that share a common transmitswitch may be referred to as a transmit beam group. Although only asingle gateway is shown in a hub-spoke spot beam group, in someembodiments, more than one gateway may be used.

The transmit switch may cycle between different switch positionsaccording to a beam group transmit switching pattern to provide forwardlink capacity to output beams associated with each of the output beamsfeeds. The beam group transmit switching pattern may be a set of switchpositions versus time during a frame.

The beam group transmit switching pattern may be stored in memory at abeam switch controller. The beam group transmit switching pattern may beuploaded to the beam switch controller using an uplink signal that maybe in-band or out-of-band with other uplink signals. The fraction oftime the transmit switch spends in each position may determine theforward link capacity provided to each beam. Flexible allocation offorward link capacity is accomplished by altering the amount of time thetransmit switch spends at each position. The time allocation may bedynamic (e.g., varying with the hour of the day) to accommodate temporalvariations of a load in each beam.

As indicated in FIG. 2A, the transmit switch may be a fast switch(capable of switching rapidly, e.g., relative to a frame describedfurther below). The switch may operate at radio frequency (RF) such asKa band frequencies. In some embodiments, a ferrite switch may be usedfor the transmit switch. Ferrite switches may provide fast switching,low insertion loss (e.g., do not adversely impact equivalentisotropically radiated power (EIRP) or gain-to-noise-temperature (G/T)),and high power handling capabilities.

Return Pathways

FIG. 2B provides an example of a return pathway in accordance with anembodiment. In this embodiment, a receive switch may select between anyone of N user beam feeds (User Feeds) or a gateway beam feed (GW/UFeed). Each of the N user beam feeds may include return signals from oneor more user terminals (e.g., user terminals 130 of FIG. 1). The gatewaybeam feed may include return signals from user terminals that arelocated within the same spot beam coverage area as the gateway terminal(hence the designation “GW/U”).). The receive switch (Rx SW) output maybe coupled to the pathway receiver. The receive switch may be before thereceiver of the pathway along a signal path. The set of beams that sharea common receive switch may be referred to as a receive beam group.

Some embodiments may include one or more LNAs before the receive switch.For example, each input beam feed may have an associated LNA with thereceive switch positioned after the LNA. Alternatively, a summer may beused to combine outputs from the LNAs, and the LNAs may be switched onand off to implement the switching function of the receive switch.

The embodiment shown in FIG. 2B may also include a transmitterconfigured to provide return downlink signals to a gateway beam feed(GW/U Feed). In the return operation, the gateway beam feed may includesignals to one or more gateway terminals (e.g., gateway terminal 115 ofFIG. 1).

The receive switch may cycle between different switch positionsaccording to a beam group receive switching pattern to provide returnlink capacity to input beams associated with each of the input beamsfeeds. The operation and control (using a beam switch controller) of thereceive switch may be similar to that of the transmit switch discussedabove.

Forward/Return Pathways

FIG. 2C provides an example of a forward/return pathway in accordancewith an embodiment. In this embodiment, a receiver may be coupled to areceive switch (Rx SW), and a transmitter may be coupled to a transmitswitch (Tx SW). The receive switch may be used to control the input tothe pathway, and the transmit switch may be used to control the outputfrom the pathway. The set of beams that share transmit and receiveswitches may be referred to as a beam group.

As discussed previously, forward link operation may be obtained byconnecting the receive switch to the gateway beam feed and cycling thetransmit switch through the output switch positions. Return linkoperation may be obtained by connecting the transmit switch to thegateway beam feed and cycling the receive switch through the inputswitch positions. According to an embodiment of the invention, the beamgroup switching patterns of the pathway shown in FIG. 2C may be arrangedsuch that a portion of a frame is dedicated to forward link operation,while another portion of the same frame is dedicated to return linkoperation.

In some embodiments, the beam group switching patterns may be the samefrom frame-to-frame (repeated in each of a plurality of consecutiveframes), while in other embodiments, the beam group switching patternsmay be changed from frame-to-frame. In yet other embodiments, aparticular beam group switching pattern may be used for a particulartime duration while another beam group switching pattern may be used fora different time duration (e.g., different times of the day, differentdays of the week, or the like). Many variations, modifications, andalternatives of switching patterns may be used within the embodimentsdisclosed herein. Whether the beam group switching patterns remain thesame or changes may depend on a desired capacity allocation amongstbeams and/or a desired ratio between forward and return capacity.

Gateway Switch Group

Recall that the set of beams that share transmit and receive switchesmay be referred to as a beam group. Beam groups may be furtheraggregated into what may be referred to as a gateway (GW) switch group.FIG. 3 is a simplified block diagram of example hardware that services aGW switch group in accordance with an embodiment of the presentinvention. The hardware may correspond to at least some of the Kpathways shown in FIG. 1. In accordance with an embodiment, a hub-spokesatellite may service a number of GW switch groups, each with a numberof receivers, transmitters, receiver switches, transmitter switches anda GW switch structure. The switches may be controlled by a beam switchcontroller as discussed previously.

The GW switch structure generally provides switching capability betweeninputs and outputs within the GW switch group. Possible inputs andoutputs of the GW switch structure include one or more of the following:(a) the inputs may be uplink signals and the outputs may be inputsignals to receive switches; (b) the inputs may be output signals fromreceivers and the outputs may be input signals to transmitters; and (c)the inputs may be output signals from transmit switches and the outputsmay be downlink signals.

As shown in FIG. 3, an embodiment includes receive switches (Rx SW) andtransmit switches (Tx SW) that are associated with the GW switch group.Each receive and transmit switch in a beam group may service the same ora different number of user beams (hence the designations “N₁” through“N_(M)”). Both receive and transmit switches may be used in thisembodiment to provide forward and return capability similar to theforward/return pathway of FIG. 2C. Some embodiments may include onlytransmit switches to provide forward link capability as in FIG. 2A. Someembodiments may include only receive switches to provide return linkcapability as in FIG. 2B.

Each receive and transmit switch is associated with a beam group and mayprovide switching between a gateway beam feed (GW/U) and a number ofuser beam feeds (U) as described previously. The GW switch structure, onthe other hand, may provide switching between input signals associatedwith one beam group and output signals associated with another beamgroup. For example, a forward uplink signal from the gateway beam feed(GW/U)₁ may be received at the receive switch Rx SW₁ and passed throughthe associated circuitry to the transmit switch Tx SW₁. From thetransmit switch Tx SW₁ the signal may be output to any of the user beamfeeds associated with that beam group. Using the receive and transmitswitches in concert with the GW switch structure, however, a forwarduplink signal from one gateway beam feed (GW/U)₁ may be switched to thetransmit switch associated with another beam depending on the GW switchstructure position. Depending on the GW switch structure capability, thesignal may be able to be output to any user beam feed associated withany of the beam groups in the GW switch group.

As the positions of the receive and transmit switches may be describedby beam group switching patterns, the positions of the GW switchstructure may be described by gateway switching patterns. The receiveand transmit beam group switching patterns may be synchronized with thegateway switching pattern to provide sequential beam switching during aframe. The beam switch controller that implements the beam groupswitching patterns on the receive and transmit switches may alsoimplement the gateway switching patterns on the GW switch structure.

The components shown in FIG. 3 may be used to implement incrementalgateway deployment in accordance with an embodiment of the invention.Incremental gateway deployment may span at least two time periods. Afirst time period during which there are fewer gateway terminals thanbeam groups (prior to a time T) is followed by a second time periodduring which at least one additional gateway terminal has been added(after time T).

During the first time period, at least P of the receivers may receive adifferent one of at least P forward link signals from P gatewayterminals GW/U (where P is a non-zero positive integer). During a frame,the GW switch structure may sequentially switch the at least P forwardlink signals from the P gateway terminals to provide the at least Pforward link signals to the transmit switches. The at least P forwardlink signals are provided to the transmit switches according to a firstgateway switching pattern, and each of the at least P forward linksignals is sequentially switched into fixed location beams according toa first beam group transmit switching pattern.

During the second time period, at least Q of the receivers may receive adifferent one of at least Q forward link signals from Q gatewayterminals GW/U (where Q is a non-zero positive integer and is greaterthan P). During a frame, the GW switch structure may sequentially switchthe at least Q forward link signals from the Q gateway terminals toprovide the at least Q forward link signals to the transmit switches.The at least Q forward link signals are provided to the transmitswitches according to a second gateway switching pattern, and each ofthe at least Q forward link signals is sequentially switched into fixedlocation beams according to a second beam group transmit switchingpattern.

Gateway terminals may transmit forward link signals to the satelliteusing a single polarization or more than one polarization (e.g., righthand circular polarized (RHCP) and left hand circular polarized (LHCP)).Using more than one polarity may increase capacity and decreaseinterference. Referring to the example, in some embodiments the at leastP receivers may consist of exactly P receivers and the P gatewayterminals may each transmit one signal on a single polarization. Inother embodiments, the at least P receivers may consist of exactly 2*Preceivers and the P gateway terminals may each transmit two signals ontwo different polarizations.

This embodiment has discussed a forward traffic embodiment. Similartechniques may be used for return traffic, and for combinedforward/return traffic.

Switch Matrix Groups

FIG. 4 is a simplified block diagram of a GW switch group embodiment,employing a switch matrix to provide incremental gateway deployment forforward and return link capability at a hub-spoke satellite inaccordance with an embodiment of the present invention. This embodimentshows a GW switch group that includes M pathways with M receivers (Rx)and M transmitters (Tx). The hardware may correspond to M of the Kpathways shown in FIG. 1 (M<K). Receive antenna feeds, beam switchcontroller, etc. shown in previous figures and described previously arenot shown in this embodiment to avoid unnecessarily cluttering thefigure. An M×M switch matrix may provide the GW switch structure in thisembodiment. The M×M switch matrix may be configured to direct an outputsignal from any one of the M receivers to an input of any one of the Mtransmitters. A switch matrix may be implemented by an array of low masssolid state switches with hybrids.

In an example of the capability provided by a switch matrix, an inputsignal received at the receive switch (Rx SW) on the upper left of FIG.4 may be output from the transmit switch (Tx SW) on the upper right ofFIG. 4 or from the transmit switch on the lower right of FIG. 4depending on the setting of the M×M switch matrix.

As shown in FIG. 4, fixed location beams associated with each receiveswitch and each transmit switch may include N user beams (U) and agateway beam (GW/U). Feeds (such as the N User Feeds and the GW/U feedsshown in FIG. 2B) may be coupled to inputs of each receive switch shownin FIG. 4. Signals from the fixed location beams are passed from thesefeeds to the receive switches. Feeds (such as the N User Feeds and theGW/U feeds shown in FIG. 2A) may be coupled to outputs of each transmitswitch shown in FIG. 4. Signals to the fixed location beams are passedfrom the transmit switches to these feeds. Note that each receive switch(or each transmit switch) may service the same number of user beams or adifferent number of user beams (hence the designations “N₁” and“N_(M)”). The receive switches and the transmit switches may beconfigured for fast switching as described above.

In a first mode of operation, the M×M switch matrix may be fixed to passsignals directly through from left to right, such that the signals toand from each gateway terminal will take a similar path to that shown inFIG. 2C. In this mode of operation, each gateway terminal may providecapacity only to users in its beam group. In other modes of operation,the M×M switch matrix may synchronize its switching pattern to thereceive and transmit beam group switching patterns. Thus, the serviceslots from one gateway may be allocated to any beam within the GW switchgroup, regardless of beam group association.

To understand use of the switch matrix in a gateway deployment, anexample of an incremental gateway deployment will be described.Initially, a first gateway terminal GW1 is the only gateway terminaldeployed. It is associated with N₁ user beams U and one combined gatewayand user beam (GW/U)₁. Here, P=1. Since the gateway terminal GW1 is theonly gateway terminal that is initially deployed, it cannot provideservice to users associated with other gateways if the first mode ofswitch matrix operation described above is employed. The switch matrixmay be controlled, however, to sequentially switch an output from thesingle receiver associated with the gateway terminal GW1 to inputs oftransmitters associated with all the other gateway terminals in the GWswitch group. This is for forward traffic slots. For return trafficslots, the M×M switch matrix may be controlled to sequentially switchoutputs from each of the M receivers to the input of the singletransmitter associated with gateway terminal GW 1. Thus, the capacityprovided by the gateway terminal GW1 may be allocated across all beamsin the GW switch group as desired.

Continuing with this example, at a later time (after a time T) anotherM−2 gateway terminals are deployed such that only GW_(M) is notoperational. Now, P=M−1. In this scenario, the M×M switch matrix may becontrolled to sequentially switch outputs from the first M−1 receiversto inputs of all the transmitters (for forward traffic slots). Forreturn traffic slots, the switch matrix may be controlled tosequentially switch outputs from each of the M receivers to inputs ofthe first M−1 transmitters. Thus, the capacity provided by the first M−1gateway terminals may be allocated across all user beams in the GWswitch group as desired.

Outer Switch Groups

FIG. 5 is a simplified block diagram of a GW switch group embodimentusing an outer switch structure that may be used to provide incrementalgateway deployment for forward and return link capability at a hub-spokesatellite in accordance with an embodiment of the present invention.This embodiment uses a hardware pathway that includes a receiver (Rx)and a transmitter (Tx). As explained above, the receiver may include anLNA, and the transmitter may include a HPA. The pathway may correspondto one of the K pathways shown in FIG. 1. Receive antenna feeds, beamswitch controller, etc. shown in previous figures and described aboveare not shown in this embodiment to avoid unnecessarily cluttering thefigure.

In this embodiment, the receiver is coupled to a receive switch (RxSwitch), and the receive switch is coupled to a receive-side outerswitch (Rx Outer Switch). The receive switch may sequentially switchsignals from fixed location beams into a receiver according to a beamgroup receive switching pattern. The fixed location beams in thisembodiment include three user beams (Beam A, Beam B, Beam C) and agateway beam (GW/U)₁. The receive-side outer switch may sequentiallyswitch signals from fixed location gateway beams (GW/U)₁ to (GW/U)_(M)into an input (GW/U)′₁ of the receive switch for the pathway accordingto a gateway switching pattern. Each of the gateway beams may alsoservice user terminals that are located within the gateway beams. Thereceive-side outer switch may be coupled to other pathways through otherreceive switches as indicated by arrows extending from the right-side ofthe receive-side outer switch.

The transmitter is coupled to a transmit switch (Tx Switch), and thetransmit switch is coupled to a transmit-side outer switch (Tx OuterSwitch). The transmit switch may sequentially switch signals into fixedlocation beams according to a beam group transmit switching pattern. Thefixed location beams in this embodiment include three user beams (BeamA, Beam B, Beam C) and a gateway beam (GW/U)₁. The transmit-side outerswitch may sequentially switch signals from an output (GW/U)′₁ of thetransmit switch for the gateway beam into fixed location gateway beams(GW/U)₁ to (GW/U)_(M) according to a gateway switching pattern. Each ofthe gateway beams may also service user terminals that are locatedwithin the gateway beams. The transmit-side outer switch may be coupledto other pathways through transmit switches as indicated by arrowspointing into the left side of the transmit-side outer switch.

The GW switch structure in this embodiment may comprise the receive-sideouter switch (forward traffic), the transmit-side outer switch (returntraffic), or both (forward and return traffic). The receive-side outerswitch and the transmit-side outer switch may be used in tandem toenable forward and return incremental gateway deployment in a mannersimilar to that described previously.

FIG. 6 is a simplified block diagram of a first outer switch networksembodiment that may be used to enable incremental gateway deployment forforward and return link capability at a hub-spoke satellite inaccordance with an embodiment of the present invention. The outer switchnetworks (GW switch structure) in this embodiment may includereceive-side outer switches (forward traffic), transmit-side outerswitches (return traffic), or both (forward and return traffic). Signalsfrom a first input gateway beam (GW/U)₁ may be switched between pathwaysassociated with any of the output gateway beams (GW/U)₁, (GW/U)₂,(GW/U)₃, and (GW/U)₄. This allows capacity from a gateway terminal GW1located within the first gateway beam (GW/U)₁ to be shared amongst userbeams associated with output gateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃,and (GW/U)₄.

This embodiment shows a first layer 1:4 receive-side outer switchconfigured to switch signals associated with the first input gatewaybeam (GW/U)₁. One output of the 1:4 receive-side outer switch is labeled(GW/U)′₁ and goes to the (GW/U)′₁ input of the receive switch of FIG. 5,while the other three outputs become inputs to second layer 2:1receive-side outer switches, each of which is configured to switchbetween the (GW/U)₁ signal and a signal from one of the other inputgateway beams (GW/U)₂, (GW/U)₃, and (GW/U)₄. Outputs of each of the 2:1receive-side outer switches labeled (GW/U)′₂, (GW/U)′₃, and (GW/U)′₄ arecoupled to the pathways associated with the respective gateways.

The 2:1 receive-side outer switches and 1:2 transmit-side outer switchesshown in FIG. 6 may be configured for fast switching or “slow” switchingif, for example, they only switch when an associated gateway isdeployed, which is infrequent compared to the time duration of a frame.The Rx network may be low power and low loss. The Tx network may be highpower and low loss.

As an example, if the gateway terminal GW1 located in the first gatewaybeam (GW/U)₁ is the only gateway terminal deployed, the 1:4 and 4:1outer switches shown in FIG. 6 may sequentially switch between eachpathway (each associated with a beam group) during a frame. Since thereare four pathways in this embodiment (one associated with each of thegateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and (GW/U)₄), each pathway mayreceive an average of 25% of the capacity from the gateway terminal GW1located in the first gateway beam (GW/U)₁. The actual capacity for eachpathway may vary since the switches allow flexible allocation ofcapacity as needed.

If gateway terminals GW1 and GW2 located in the first and second gatewaybeams (GW/U)₁ and (GW/U)₂ are the only gateway terminals deployed, thepathway associated with the second gateway beam (GW/U)₂ may receive 100%of the capacity from the gateway terminal GW2 located in the secondgateway beam (GWU)₂. The pathways associated with the gateway beams(GW/U)₁, (GW/U)₃, and (GW/U)₄ may each receive an average of 33% of thecapacity from the gateway terminal GW1 located in the first gateway beam(GW/U)₁, by using the 1:4 and 4:1 outer switches to sequentially switchbetween the three corresponding pathways during a frame.

If gateway terminals GW1, GW2, and GW3 located in the first, second, andthird gateway beams (GW/U)₁, (GW/U)₂, and (GW/U)₃ are the only gatewayterminals deployed, the pathways associated with the second and thirdgateway beams (GW/U)₂ and (GW/U)₃ may each receive 100% of the capacityfrom their respective gateway terminals GW2 and GW3 located in thesecond and third gateway beams (GW/U)₂ and (GW/U)₃. The pathwaysassociated with the gateway beams (GW/U)₁ and (GW/U)₄ may each receivean average of 50% of the capacity from the gateway terminal GW1 locatedin the first gateway beam (GW/U)₁, by using the 1:4 and 4:1 outerswitches to sequentially switch between the two corresponding pathwaysduring a frame.

Once gateway terminals GW1, GW2, GW3, and GW4 located in each of thegateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and (GW/U)₄ are deployed, thepathway associated with each of the gateway beams (GW/U)₁, (GW/U)₂,(GW/U)₃, and (GW/U)₄ may receive 100% of the capacity from theirrespective gateway terminals.

The 1:4 receive-side outer switch and the 4:1 transmit-side outer switchare used in this embodiment to provide switching for the four pathways.In general, a 1:R receive-side outer switch and a R:1 transmit-sideouter switch may be used in accordance with this embodiment to provideswitching for R pathways.

FIG. 7 is a simplified block diagram of a second outer switch networksembodiment that may be used to enable incremental gateway deployment forforward and return link capability at a hub-spoke satellite inaccordance with an embodiment of the present invention. This embodimentfeatures more switches than the first outer switch networks embodiment,but it allows for a uniform distribution of capacity as the gateways aredeployed. The outer switch networks (GW switch structure) in thisembodiment may include receive-side outer switches (forward traffic),transmit-side outer switches (return traffic), or both (forward andreturn traffic). In some embodiments, this allows capacity to be sharedbetween any of the gateway beams (GW/U)₁-(GW/U)₄ and amongst user beamsassociated with output gateway beams (GW/U)₁-(GW/U)₄.

This embodiment shows a first layer (or bank) of receive-side outerswitches that include 1:4, 1:3, 1:2 switches and a second layer (orbank) of receive-side outer switches that include 2:1, 3:1, 4:1switches. In general, 1:R, 1:(R−1), . . . 1:2 switches may be used forthe first layer of receive-side outer switches, and R: 1, (R−1): 1, . .. 2:1 switches may be used for the second layer of receive-side outerswitches, for R pathways. The Rx network may be low power and low loss.The Tx network may be high power and low loss.

This embodiment also shows a first layer of transmit-side outer switchesthat include 4:1, 3:1, 2:1 switches and second layer of transmit-sideouter switches that include 4:1, 3:1, 2:1 switches. In general, 1:R,1:(R−1), . . . 1:2 switches may be used for the first layer oftransmit-side outer switches, and R: 1, (R−1): 1, . . . 2:1 switches maybe used for the second layer of transmit-side outer switches, for Rpathways.

The first layer of receive-side outer switches may be configured forfast switching as described above. The second layer of receive-sideouter switches may be configured for fast switching or some of them maybe configured for slow switching if, for example, they only switch whenan associated gateway is deployed, which is infrequent compared to thetime duration of a frame.

As an example, if a gateway terminal GW1 located in a first gateway beam(GW/U)₁ is the only gateway terminal deployed, the outer switches shownin FIG. 7 may sequentially switch between beam groups associated witheach pathway. Since there are four pathways in this embodiment (oneassociated with each of the gateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and(GW/U)₄), each pathway may receive an average of 25% of the capacityfrom the gateway terminal GW1 located in the first gateway beam (GW/U)₁.The actual capacity for each pathway may vary since the switches allowflexible allocation of capacity as needed. For example, with only thefirst gateway terminal GW1 deployed, user beams associated with thefirst gateway terminal GW1 and user beams associated with just one othergateway terminal may need service. In that case, the capacity from thefirst gateway terminal GW1 would be allocated amongst only those beamsand not the remaining beams associated with other gateway terminals.

If gateway terminals GW1 and GW2 located in the first and second gatewaybeams (GW/U)₁ and (GW/U)₂ are the only gateway terminals deployed, thepathways associated with the second and third gateway beams (GW/U)₂ and(GW/U)₃ may each receive an average of 50% of the capacity from thegateway terminal GW2 located in the second gateway beam (GW/U)₂ bysetting the slow 2:1, 3:1 and 1:2, 1:3 switches to the signalscorresponding to the second gateway beam (GW/U)₂ and having the firstlayer 1:3 receive-side outer switch sequentially switch between thepathways corresponding to (GW/U)₂ and (GW/U)₃. The pathways associatedwith the gateway beams (GW/U)₁ and (GW/U)₄ may each receive an averageof 50% of the capacity from the gateway terminal GW1 located in thefirst gateway beam (GW/U)₁ using similar techniques. Note that thegateway terminal GW2 located in the second gateway beam (GW/U)₂ mayalternatively service the user terminals from the beam group of thefourth gateway beam (GW/U)₄.

If gateway terminals GW1, GW2, and GW3 located in the first, second, andthird gateway beams (GW/U)₁, (GW/U)₂, and (GW/U)₃ are the only gatewayterminals deployed, the pathways associated with the gateway beams(GW/U)₁, (GW/U)₂, (GW/U)₃, and (GW/U)₄ may each receive an average of75% of pathway capacity. By sequential switching as discussed above,gateway terminals GW1, GW2, and GW3 located in the first, second, andthird gateway beams (GW/U)₁, (GW/U)₂, and (GW/U)₃ may each provide 75%of their capacity to the pathways associated with their respectivegateway beams and 25% of their capacity to the pathway associated withthe fourth gateway beam (GW/U)₄. The 4:1 switch in the second layer ofreceive-side outer switches and the 1:4 switch in the second layer oftransmit-side outer switches may be configured for fast switching toreceive signals from each of the first, second, or third gateway beams(GW/U)₁, (GW/U)₂, and (GW/U)₃ during a frame.

If gateway terminals GW1, GW2, GW3, and GW4 located in each of thegateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and (GW/U)₄ are deployed, thepathway associated with each of the gateway beams (GW/U)₁, (GW/U)₂,(GW/U)₃, and (GW/U)₄ may receive 100% of the capacity from theirrespective gateway terminals. If fast switches are employed for all theswitches in the second outer switch networks, however, any gateway mayprovide any fraction of its capacity to any other beam by properscheduling of the switches.

FIG. 8 is a simplified block diagram of a third outer switch networksembodiment that may be used to enable incremental gateway deployment forforward and return link capability at a hub-spoke satellite inaccordance with an embodiment of the present invention. This embodimentfeatures more switches than the first outer switch networks embodiment,and it provides a more uniform distribution of capacity as the gatewaysare deployed. This embodiment features less switches than the secondouter switch networks embodiment, and it provides a less uniformdistribution of capacity as the gateways are deployed. It may beconsidered a compromise between implementation complexity andflexibility. The outer switch networks (GW switch structure) in thisembodiment may include receive-side outer switches (forward traffic),transmit-side outer switches (return traffic), or both (forward andreturn traffic). In some embodiments, this allows capacity to be sharedbetween any of the gateway beams (GW/U)₁-(GW/U)₄ and amongst user beamsassociated with output gateway beams (GW/U)₁-(GW/U)₄.

This embodiment shows a first layer of receive-side outer switches thatinclude 1:4 and 1:2 switches and a corresponding first layer oftransmit-side outer switches that include 4:1 and 2:1 switches. Thisembodiment also shows a second layer of receive-side outer switches thatinclude 2:1, 3:1, and 2:1 switches and a corresponding second layer oftransmit-side outer switches that include 1:2, 1:3, and 1:2 switches.

The first layer of switches may be configured for fast switching asdescribed above. The second layer of switches may be configured for fastswitching or slow switching if, for example, they only switch when anassociated gateway is deployed, which is infrequent compared to the timeduration of a frame. The Rx network may be low power and low loss. TheTx network may be high power and low loss.

As an example, if a gateway terminal GW1 located in the first gatewaybeam (GW/U)₁ is the only gateway terminal deployed, the outer switchesshown in FIG. 8 may switch between beam groups associated with eachpathway. Since there are four pathways in this embodiment (oneassociated with each of the gateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and(GW/U)₄), each pathway will receive an average of 25% of the capacityfrom the gateway terminal GW1 located in the first gateway beam (GW/U)₁.The actual capacity for each pathway may vary since the switches allowflexible allocation of capacity as needed.

If gateway terminals GW1 and GW2 located in the first and second gatewaybeams (GW/U)₁ and (GW/U)₂ are the only gateway terminals deployed, thepathway associated with the second and third gateway beams (GW/U)₂ and(GW/U)₃ may each receive an average of 50% of the capacity from thegateway terminal GW2 located in the second gateway beam (GW/U)₂ bysetting the slow 2:1, 3:1 and 1:2, 1:3 switches to the signalscorresponding to the second gateway beam (GW/U)₂ and having the firstlayer 1:2 receive-side outer switch sequentially switch between thepathways corresponding to (GW/U)₂ and (GW/U)₃. The pathways associatedwith the gateway beams (GW/U)₁ and (GW/U)₄ may each receive an averageof 50% of the capacity from the gateway terminal GW1 located in thefirst gateway beam (GW/U)₁ using similar techniques. Note that thegateway terminal GW2 located in the second gateway beam (GW/U)₂ mayalternatively service the user terminals from the beam group of thefourth gateway beam (GW/U)₄.

If gateway terminals GW1, GW2, and GW3 located in the first, second, andthird gateway beams (GW/U)₁, (GW/U)₂, and (GW/U)₃ are the only gatewayterminals deployed, the pathways associated with the gateway beams(GW/U)₂ and (GW/U)₃ may each receive 100% of the capacity from theirrespective gateway terminals located in the second and third gatewaybeams GW2 and GW3 by setting their slow switches to their correspondinggateway beams (GW/U)₂ and (GW/U)₃ in a similar manner to thecorresponding case in the first outer switch networks implementation.The pathways associated with the gateway beams (GW/U)₁ and (GW/U)₄ mayeach receive an average of 50% of the capacity from the gateway terminalGW1 located in the first gateway beam (GW/U)₁ by setting the slowswitches for the (GW/U)₄ beam group to the signal from gateway beams(GW/U)₁ and having the first layer 1:4 receive-side outer switchsequentially switch between the two pathways corresponding to (GW/U)₁and (GW/U)₄.

If gateway terminals GW1, GW2, GW3, and GW4 located in each of thegateway beams (GW/U)₁, (GW/U)₂, (GW/U)₃, and (GW/U)₄ are deployed, thepathway associated with each of the gateway beams (GW/U)₁, (GW/U)₂,(GW/U)₃, and (GW/U)₄ may receive 100% of the capacity from theirrespective gateway terminals.

An example of a means for receiving the forward link signals from thegateway terminals is the receivers. An example of a means forsequentially switching the forward link signals from the gatewayterminals in the duration of one frame to provide the forward linksignals to the transmit switches is the GW switch structure. An exampleof a means for sequentially switching the forward link signals intofixed location beams according to a beam group transmit switchingpattern is the transmit switches.

Embodiments of the present invention are not limited to the examplesshown or described herein. For example, embodiments of the presentinvention may involve any number of receive-side outer switches, receiveswitches, pathways, transmit switches, and transmit-side outer switches.Also, while the above embodiments have been explained with regard to anincremental gateway deployment, the same steps may be followed inopposite order when decommissioning gateway terminals. Furthermore,features of one or more embodiments may be combined with features ofother embodiments without departing from the scope of the invention. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. Thus, the scope of thepresent invention should be determined not with reference to the abovedescription, but should be determined with reference to the appendedclaims along with their full scope of equivalents.

1-13. (canceled)
 14. A method for communicating using a hub-spokesatellite having a forward link and return link capability comprising:providing the hub-spoke satellite, the hub-spoke satellite comprising aplurality of receivers having inputs and outputs, a plurality oftransmitters having inputs and outputs, the inputs of the plurality oftransmitters coupled to the outputs of the plurality of receivers, aplurality of transmit switches coupled to the outputs of the pluralityof transmitters, a plurality of receive switches coupled to the inputsof the plurality of receivers, and a gateway switch structure coupled toone of: a) the inputs of the plurality of receivers and the outputs ofthe plurality of transmitters, and b) the outputs of the plurality ofreceivers and the inputs of the plurality of transmitters; using eachtransmit switch in the plurality of transmit switches to sequentiallyswitch a forward link signal into multiple fixed location beamsaccording to a beam group transmit switching pattern; using each receiveswitch in the plurality of receive switches to sequentially switchreturn link signals from fixed location beams into a receiver accordingto a beam group receive switching pattern; prior to a time T, using eachof the at least P receivers in the plurality of receivers to receive adifferent one of at least P forward link signals from P gatewayterminals, and in the duration of one frame, using the gateway switchstructure to sequentially switch the at least P forward link signalsfrom the P gateway terminals, in order to provide the at least P forwardlink signals to the plurality of transmit switches, according to a firstgateway switching pattern, and sequentially switching each of the atleast P forward link signals into fixed location beams according to afirst beam group transmit switching pattern; prior to time T,sequentially switching the return link signals from multiple fixedlocation beams into the plurality of receivers according to a first beamgroup receive switching pattern, and in the duration of one frame, usingthe gateway switch structure to sequentially switch the return linksignals to at least P transmitters in the plurality of transmittersaccording to the first gateway switching pattern, and using each of theat least P transmitters to transmit a different one of the return linksignals to one of the P gateway terminals; after time T, using each ofat least Q receivers in the plurality of receivers to receive adifferent one of at least Q forward link signals from Q gatewayterminals, and in the duration of one frame, using the gateway switchstructure to sequentially switch the at least Q forward link signalsfrom the Q gateway terminals, in order to provide the at least Q forwardlink signals to the plurality of transmit switches, according to asecond gateway switching pattern, and sequentially switching each of theat least Q forward link signals into fixed location beams according to asecond beam group transmit switching pattern; after time T, sequentiallyswitching the return link signals from multiple fixed location beamsinto the plurality of receivers according to a second beam group receiveswitching pattern, and in the duration of one frame, using the gatewayswitch structure to sequentially switch the return link signals to atleast Q transmitters in the plurality of transmitters according to thesecond gateway switching pattern, and using each of the at least Qtransmitters to transmit a different one of the return link signals toone of the Q gateway terminals; wherein P and Q are both non-zero,positive integers, and Q>P; and wherein the first and second gatewayswitching patterns are different. 15-27. (canceled)
 28. A satellitecommunications system having a forward link and return link capacitycomprising: a plurality of gateway terminals; a plurality of userterminals; a hub-spoke satellite for providing communications betweenthe gateway terminals and the user terminals, the hub-spoke satellitecomprising a plurality of receivers having inputs and outputs, aplurality of transmitters having inputs and outputs, the inputs of theplurality of transmitters coupled to the outputs of the plurality ofreceivers, a plurality of transmit switches coupled to the outputs ofthe plurality of transmitters, a plurality of receive switches coupledto the inputs of the plurality of receivers, and a gateway switchstructure coupled to one of: (a) the inputs of the plurality ofreceivers and the outputs of the plurality of transmitters, and (b) theoutputs of the plurality receivers and the inputs of the plurality oftransmitters; wherein each transmit switch in the plurality of transmitswitches is configured to sequentially switch a forward link signal intomultiple fixed location beams according to a beam group transmitswitching pattern; wherein each receive switch in the plurality ofreceive switches is configured to sequentially switch return linksignals from fixed location beams into a receiver according to a beamgroup receive switching pattern; wherein prior to a time T, at least Preceivers in the plurality of receivers are each configured to receive adifferent one of at least P forward link signals from P gatewayterminals, and in the duration of one frame, the gateway switchstructure is configured to sequentially switch the at least P forwardlink signals from the P gateway terminals, in order to provide the atleast P forward link signals to the plurality of transmit switches,according to a first gateway switching pattern, and each of the at leastP forward link signals is sequentially switched into fixed locationbeams according to a first beam group transmit switching pattern;wherein prior to time T, the return link signals from multiple fixedlocation beams are sequentially switched into the plurality of receiversaccording to a first beam group receive switching pattern, and in theduration of one frame, the gateway switch structure is configured tosequentially switch the return link signals to at least P transmittersin the plurality of transmitters according to the first gatewayswitching pattern, and the at least P transmitters are each configuredto transmit a different one of the return link signals to one of the Pgateway terminals; wherein after time T, at least Q receivers in theplurality of receivers are each configured to receive a different one ofat least Q forward link signals from Q gateway terminals, and in theduration of one frame, the gateway switch structure is configured tosequentially switch the at least Q forward link signals from the Qgateway terminals, in order to provide the at least Q forward linksignals to the plurality of transmit switches, according to a secondgateway switching pattern, and each of the at least Q forward linksignals is sequentially switched into fixed location beams according toa second beam group transmit switching pattern; wherein after time T,the return link signals from multiple fixed location beams aresequentially switched into the plurality of receivers according to asecond beam group receive switching pattern, and in the duration of oneframe, the gateway switch structure is configured to sequentially switchthe return link signals to at least Q transmitters in the plurality oftransmitters according to the second gateway switching pattern, and theat least Q transmitters are each configured to transmit a different oneof the return link signals to one of the Q gateway terminals; wherein Pand Q are both non-zero, positive integers, and Q>P; and wherein thefirst and second gateway switching patterns are different. 29.(canceled)
 30. The hub-spoke satellite of claim 42, wherein the at leastP receivers consist of exactly P receivers, and the P gateway terminalseach transmit one signal on a single polarization.
 31. The hub-spokesatellite of claim 42, wherein the at least P receivers consist ofexactly 2*P receivers, and the P gateway terminals each transmit twosignals on two different polarizations.
 32. The hub-spoke satellite ofclaim 42, wherein the gateway switch structure comprises a switch matrixpositioned between the plurality of receivers and the plurality oftransmitters.
 33. The hub-spoke satellite of claim 42, wherein theswitch structure comprises at least one receive-side outer switchpositioned before the plurality of receivers.
 34. The hub-spokesatellite of claim 33, wherein the plurality of receivers comprises Rreceivers, R being a non-zero, positive integer, and R>=Q>P; wherein theat least one receive-side outer switch comprises: one 1:R switch forreceiving a first forward link signal, the 1:R switch associated with afirst switching speed allowing switching within the duration of oneframe; and a plurality of 2:1 switches, each for receiving (a) an outputof the 1:R switch and (b) one of R−1 other forward link signals, each ofthe plurality of 2:1 switches associated with a second switching speedallowing switching at time T.
 35. The hub-spoke satellite of claim 33,wherein the plurality of receivers comprises R receivers, R being anon-zero, positive integer, and R>=Q>P; wherein the at least onereceive-side outer switch comprises: a first bank of switches, including1:R, 1:(R−1), . . . , 1:2 switches, each associated with a firstswitching speed allowing switching within the duration of one frame; asecond bank of switches following the first bank of switches, the secondbank of switches including 2:1, 3:1, . . . , (R−1):1 switches, eachassociated with a second switching speed allowing switching at time T,the second bank of switches further including an R:1 switch associatedwith the first switching speed allowing switching within the duration ofone frame.
 36. The hub-spoke satellite of claim 33, wherein theplurality of receivers comprises R receivers, R being a non-zero,positive integer, and R>=Q>P; wherein the at least one receive-sideouter switch comprises: a first bank of switches, including a 1:R switchand a 1:(R/2) switch, each associated with a first switching speedallowing switching within the duration of one frame; a second bank ofswitches following the first bank of switches, each associated with asecond switching speed allowing switching at time T.
 37. The hub-spokesatellite of claim 42, wherein each of the plurality of receiverscomprises a low noise amplifier (LNA).
 38. The hub-spoke satellite ofclaim 42, wherein each of plurality of transmitters comprises a highpower amplifier (HPA).
 39. The hub-spoke satellite of claim 42, whereinthe first and second beam group transmit switching patterns aredifferent.
 40. The hub-spoke satellite of claim 42, wherein the firstand second beam group transmit switching patterns are the same. 41.(canceled)
 42. A hub-spoke satellite having a forward link and returnlink capacity comprising: a plurality of receivers having inputs andoutputs; a plurality of transmitters having inputs and outputs, theinputs of the plurality of transmitters coupled to the outputs of theplurality of receivers; a plurality of transmit switches coupled to theoutputs of the plurality of transmitters; a plurality of receiveswitches coupled to the inputs of the plurality of receivers; a gatewayswitch structure coupled to one of: (a) the inputs of the plurality ofreceivers and the outputs of the plurality of transmitters, and (b) theoutputs of the plurality receivers and the inputs of the plurality oftransmitters; wherein each transmit switch in the plurality of transmitswitches is configured to sequentially switch a forward link signal intomultiple fixed location beams according to a beam group transmitswitching pattern; wherein each receive switch in the plurality ofreceive switches is configured to sequentially switch return linksignals from fixed location beams into a receiver according to a beamgroup receive switching pattern; wherein prior to a time T, at least Preceivers in the plurality of receivers are each configured to receive adifferent one of at least P forward link signals from P gatewayterminals, and in the duration of one frame, the gateway switchstructure is configured to sequentially switch the at least P forwardlink signals from the P gateway terminals, in order to provide the atleast P forward link signals to the plurality of transmit switches,according to a first gateway switching pattern, and each of the at leastP forward link signals is sequentially switched into fixed locationbeams according to a first beam group transmit switching pattern;wherein prior to time T, the return link signals from multiple fixedlocation beams are sequentially switched into the plurality of receiversaccording to a first beam group receive switching pattern, and in theduration of one frame, the gateway switch structure is configured tosequentially switch the return link signals to at least P transmittersin the plurality of transmitters according to the first gatewayswitching pattern, and the at least P transmitters are each configuredto transmit a different one of the return link signals to one of the Pgateway terminals; wherein after time T, at least Q receivers in theplurality of receivers are each configured to receive a different one ofat least Q forward link signals from Q gateway terminals, and in theduration of one frame, the gateway switch structure is configured tosequentially switch the at least Q forward link signals from the Qgateway terminals, in order to provide the at least Q forward linksignals to the plurality of transmit switches, according to a secondgateway switching pattern, and each of the at least Q forward linksignals is sequentially switched into fixed location beams according toa second beam group transmit switching pattern; wherein after time T,the return link signals from multiple fixed location beams aresequentially switched into the plurality of receivers according to asecond beam group receive switching pattern, and in the duration of oneframe, the gateway switch structure is configured to sequentially switchthe return link signals to at least Q transmitters in the plurality oftransmitters according to the second gateway switching pattern, and theat least Q transmitters are each configured to transmit a different oneof the return link signals to one of the Q gateway terminals; wherein Pand Q are both non-zero, positive integers, and Q>P; and wherein thefirst and second gateway switching patterns are different. 43.(canceled)
 44. The hub-spoke satellite of claim 56, wherein the meansfor receiving the at least P forward link signals consists of exactly Preceivers, and the P gateway terminals each transmit one signal on asingle polarization.
 45. The hub-spoke satellite of claim 56, whereinthe means for receiving each of at least P forward link signals consistsof exactly 2*P receivers, and the P gateway terminals each transmit twosignals on two different polarizations.
 46. The hub-spoke satellite ofclaim 56, wherein the means for sequentially switching the at least Pforward link signals according to the first gateway switching patternand sequentially switching the at least Q forward link signals accordingto the second gateway switching pattern comprises a switch matrixpositioned between the plurality of receivers and the plurality oftransmitters.
 47. The hub-spoke satellite of claim 56, wherein the meansfor sequentially switching the at least P forward link signals accordingto the first gateway switching pattern and sequentially switching the atleast Q forward link signals according to the second gateway switchingpattern comprises at least one receive-side outer switch positionedbefore the plurality of receivers.
 48. The hub-spoke satellite of claim47, wherein the plurality of receivers comprises R receivers, R being anon-zero, positive integer, and R>=Q>P; wherein the at least onereceive-side outer switch comprises: one 1:R switch for receiving afirst forward link signal, the 1:R switch associated with a firstswitching speed allowing switching within the duration of one frame; anda plurality of 2:1 switches, each for receiving (a) an output of the 1:Rswitch and (b) one of R−1 other forward link signals, each of theplurality of 2:1 switches associated with a second switching speedallowing switching at time T.
 49. The hub-spoke satellite of claim 47,wherein the plurality of receivers comprises R receivers, R being anon-zero, positive integer, and R>=Q>P; wherein the at least onereceive-side outer switch comprises: a first bank of switches, including1:R, 1:(R−1), . . . , 1:2 switches, each associated with a firstswitching speed allowing switching within the duration of one frame; asecond bank of switches following the first bank of switches, the secondbank of switches including 2:1, 3:1, . . . , (R−1):1 switches, eachassociated with a second switching speed allowing switching at time T,the second bank of switches further including an R:1 switch associatedwith the first switching speed allowing switching within the duration ofone frame.
 50. The hub-spoke satellite of claim 47, wherein theplurality of receivers comprises R receivers, R being a non-zero,positive integer, and R>=Q>P; wherein the at least one receive-sideouter switch comprises: a first bank of switches, including a 1:R switchand a 1:(R/2) switch, each associated with a first switching speedallowing switching within the duration of one frame; a second bank ofswitches following the first bank of switches, each associated with asecond switching speed allowing switching at time T.
 51. The hub-spokesatellite of claim 56, wherein the means for receiving the at least Pforward link signals comprises at least one low noise amplifier (LNA).52. The hub-spoke satellite of claim 56, wherein the means for receivingthe at least Q forward link signals comprises at least one low noiseamplifier (LNA).
 53. The hub-spoke satellite of claim 56, wherein thefirst and second beam group transmit switching patterns are different.54. The hub-spoke satellite of claim 56, wherein the first and secondbeam group transmit switching patterns are the same.
 55. (canceled) 56.A hub-spoke satellite having a forward link and return link capabilitycomprising: prior to a time T: means for receiving at least P forwardlink signals from P gateway terminals; means for sequentially switchingthe at least P forward link signals from the P gateway terminals in theduration of one frame, in order to provide the at least P forward linksignals to a plurality of transmit switches, according to a firstgateway switching pattern; means for sequentially switching each of theat least P forward link signals into fixed location beams according to afirst beam group transmit switching pattern; means for sequentiallyswitching return link signals from multiple fixed location beams into aplurality of receivers according to a first beam group receive switchingpattern; means for sequentially switching the return link signals to atleast P transmitters in the duration of one frame, according to thefirst gateway switching pattern; means for transmitting the return linksignals to one of the P gateway terminals; after time T: means forreceiving at least Q forward link signals from Q gateway terminals;means for sequentially switching the at least Q forward link signalsfrom the Q gateway terminals in the duration of one frame, in order toprovide the at least Q forward link signals to the plurality of transmitswitches, according to a second gateway switching pattern; means forsequentially switching each of the at least Q forward link signals intofixed location beams according to a second beam group transmit switchingpattern; means for sequentially switching the return link signals frommultiple fixed location beams into the plurality of receivers accordingto a second beam group receive switching pattern; means for sequentiallyswitching the return link signals to at least Q transmitters in theduration of one frame, according to a second gateway switching pattern;means for transmitting the return link signals to one of the Q gatewayterminals; wherein P and Q are both non-zero, positive integers, andQ>P; and wherein the first and second gateway switching patterns aredifferent.